Resistance to change -- with this? (8)

I believe the answer is:

rheostat

I'm a little stuck... Click here to teach me more about this clue!

'resistance' is the definition.
(I know that rheostat is a type of resistance)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for rheostat that I've seen before include "Variable resistance" , "Resistor for regulating current" , "Electrical controller" , "Electrical device" , "Variable resistor" .)

I've seen this clue in The Telegraph.

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